Plant and device for fluid control



June 9, 1942. J. MERCIER 2,285,604

PLANT AND DEVICE FOR FLUID CONTROL Filed Feb. 28, 1940 "(Emil I wu. 3%

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UNITED 1 STATES PATENT OFFICE ennu runrr srib nnvrcn ma rwm con'raor.

Jean Mercler, Nellilly-sur-Seine, France Y Application February 28, 1040,8erial No. 321,286

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5 Claims. (01.60-51) The present invention relates w devices for the fluid pressure control of parts or mechanisms adapted to occupy either of two different posi- -nism (for instance a retractable landing gear) into one of the two positions (always the same) in case of the ormal control means failing to work for any reason.

Other objects of the present-invention will result from the following detailed description'of some specific embodiments thereof.

with line a, while it connects line It with-return line 12.

' Reference numerals Ila and 20 designate the two parts to be controlled by the device according to the invention. It will be for instance supposed that they are elements of a retractable landing gear.

These elements Ito and 22 are respectively carried by pistons llb'and 22b. mounted in the tion adapted to be used in connection with said embodiment; Y

Fig. 3 is a diagrammatic view of a storage tank for fluid adapted to be used in connection with In.-Flg..1, reference-character I designates a tank for oil or another fluid. This tank I is connected with a pump 2, which is in turn connected through a check .valve. 2 with the lower chamber 6 of a storage tank 4, the other chamber I of which is separated from chamber 8 by a movable partition 5. Chamber I is, for instance, filled with compressed air. 5

corresponding cylinders ll and 20.

Now, line 22 communicates, through branch .lines 2! and 32, with the portions .of said cylinders located under the respective pistons. On the other hand, line I4 is adapted to communicate, through branch lines II and it, with chambers 2|, opening respectively into the portions of the cylinders located above their pistons. Another line 21, called the auxiliary line, is also adapted to communicate, through branch lines 22 and 22, with said chambers 2!, respectively.

Each of these chambers 2| is fitted with valve means for connecting it, alternately, either to line It (or I) or to line 22 (or 22) according as the pressure in each of these lines is higher than the pressure in the other. In other words. when the pressure in line II (or I) is higher than the pressure in line 22 (or 23), said valve means opens the connection between II (or It) and chamber 21 and simultaneously closes the connection between said chamber and 22 (or 23). Alternately, when the pressure in 22 (or 22) is vhigher than the pressure in II (or Ii) the valve means opens the connection between 22 or 22) and chamber 2|, while closing the connection bemeans, constituted for instance by a ball '2, to-

Chamber C communicates through a line I fitted with a check valve II with the distributor means II. A pressure gauge I is advantageously connected to line I; The distributor means consists of a a.-'-Line 2' above mentioned; v b.-Return line I2. leading .back to tank I c.-'--Main feed line u; and

-d.--Main feed line 3..

Valve ll iscontrolled by member Ila so asto - be brought'into at least two-different positions.

In its flrst'position} valve ll connects line I with line H, while it'connects line 2| with re- ;turn line l2.

In its: second p sition, valve ll connects line t reversin valve ll cooperating with the following lines:

wardthe position closing the connection between 2! and 22 (or-22), so that, in order to open this connection, the pressure in line 22 (or 22) must be higher than the pressure in line It (or It) by equaltothestrengthofsaid an amount at 'least' spring. v Line 21 is connected to a source of fluid pressure, with the interposition of a cock between said line and saidsource.

For instance, line 21 is filled with oil and opens,- at the top, into a chamber ll, partly filled with said oil, and the top portion of which, filled with compressed air. can communicate, through a line 21a controlled by a cock 21b (and advantageously fittedwithapressuregaugea) withthetop' chamberlofstoragetankL'Theprssurein chamberflhavingbecnmadeequaltothatin chamber'lbyopeningcockllb forashort time,

,'this cock is then closed for the operation of the device. If, after a time, gauge 29 shows a substantial drop of the pressure in chamber 48 (for the position of the parts illustrated by the drawing) cock 21b is again opened for a short time so as to restore the pressure in chamber 48 to its proper value. But it should be well understood that any other source of pressure might be used according to the invention. For instance, chamber 48 might be closed at the top, forming a compressed air reservoir wholly independent of storage tank 4.

This device works in the following manner:

According as valvev I I is in one position or the other, oil under pressure from line 8 will be fed eitherunder or above the pistons, while the respective opposed faces of said pistons are connected to the return line I2. Accordingly the pistons will be brought into either the upper or the lower position, according to the position given to control member IIa.

When valve II is in the position connecting line 8 with line 38, cock 28 is kept clbsed. There is no pressure tending to lift valves 25 from their lower seats. On the contrary, when valve II is in the other position (connecting line 8 with line I4) cock 28 must be opened, either manually or otherwise. But the sum of the pressure in line I5 and I6 and of the strength of spring 26 is higher than the pressure in line 21. Valves 25 therefore remain, in this case also, in their lower positions.

This is the normal operation.

If now, when line I4 is being connected through valve I I with line 8, in order to bring the pistons to their lower positions, some damage occurs to the normal control circuit (breakdown of pump 2, bursting or leakage of line I4 or line 8, etc.) and since, at this time cock 28 is open, the pressure in line 21 is new higher than the pressure in lines I5 and I8 by a considerable amount (more than sufficient to overcome the resistance of springs 25) balls 25 are lifted from their lower seats. Thus, they open the connection between chambers 2I on the one hand and lines 22 and 23 respectively on the other hand, and at the same time they close the connections between said chambers 2| and lines I5 and I8 respectively, and the pressure of line 21, transmitted to the upper chambers of cylinders I8 and 28 pushes the corresponding pistons I9b'and 28b into their lower positions.

Thus, in case of failure of the normal control means to bring the landing gear into one given position, auxiliary conduit 21 automatically remedies this failure.

It should be noted that if, after thus bringing the pistons into their'lower positions, cock 28 is closed, it becomes impossible to bring back the pistons to their upper, positions because, when line 38 is then connected through valve II with feed line 8, the fluid pressure fed through 3I and 32 under the pistons can no longer have any effect. This is due to the fact that the oil above said pistons cannot escape through I5 and I6 (since balls 25 are in their upper positions) nor through line 21, which is entirely filled with oil without any possible exhaust (since cook 28 is closed).

Therefore, if, after pistons I91) and 28b have been lowered through the action of the pressure in auxiliary line 21; cock 28 is closed, said pistons remain hydraulically locked in this position, even I if line 38 is not injured and is connected with line A 8 through valve II. The same locking can obtained at will in the absence of any injury to line I4 if valve II has a neutral position in which it connects both of lines I4 and 38 with discharge line I2. In this case, it sumces to open cock 28 until the pistons are lowered by the pressure in 21 and then to close it again. The pistons are then looked in their lower positions.

It is thus clear that the device according to. the invention permits of locking a landing gear in one of its positions, irrespective of the displacements which are then imparted to the control member IIa of distributor valve II.

However, it will be understood that, under normal working conditions, cock 28 should be opened when valve I I is in the position connecting I4 with 8, and closed when valve II is in the position cutting off I4 from 8. Thus the emergency means constituted by line 21 are ready to operate as long as I4 is supplied with fluid pressure, but they do not prevent the action of fluid pressure fed through line 88, when I4 is cut off from 8. l

But, on the other hand, if after the opening of cock 28, occurring simultaneously with the plac ing of control member IIa into the position connecting line I4 with line 8, there is a pressure drop in line I4 so that the auxiliary pressure source is caused to operate through line 21 as the position connecting line 38 with line 8 should 'not be accompanied by the closing of cook 28.

Because, if in this case, cook 28 remains open, and provided, of course, that line 38 is not injured, the pistons can still be operated in both directions, as follows: when fluid pressure is supplied to line 38 and below the pistons, the oil above said pistons can escape from the cylinders into pipes 22 and 23 and pipe 21 because cock 28 is open and the back flow of oil through 21 merely produces an elastic compression of the air entrapped in the top part of cylinder 48 (which air has precedingly expanded) in order to drive pistons I91: and 28b downwardly when the main supply line I4 has failed to feed liquid under pressure, The upward movement of the pistons isfurther made possible by the fact that the pressure in 21 is limited while the pressure in 38, supplied by pump 2, can be increased as desired.

Therefore, if, after the emergency means (line 21 and air cushion in 48) have been called into play by a deterioration of line I4, cook 28 remains open, it is still possible either to lift the pistons, by connecting .38 with 8 through II, or to lower them, by cutting of! this connection, the operation being then produced by the pressure accumulated in 48.

The invention therefore provides means for automatically controlling the operation of cock 28 in response both to displacements of control member Ho and to accidental variations of pressure in I4.

These means must comply with the followin conditions:

In all cases, when Ila is operated to bring line I4 into communication with line 8, cock 28 must be opened simultaneously.

When, inversely, control member- Ila is operated to close the communication between I4 and 8 and to open the communication between 38 and 8,'two cases may occur:

a.--If, at this time, line I4 is uninjured, that is to say is under pressure, this return movement of Na must bring back cock 28 into the closed position; v

n+1: pipe I4 is injured so that it is no longer under pressure this movement of Ila mustleave cook 23 open.

Connecting means between Ila and 23 complying with these conditions are shown by the drawing.

Control member Ila is connected with a sliding part 45, mounted in a guide 45. Part 45 carries a cylinder 41, provided with a plunger piston 52. Cylinder" is connected at its lower end with a line l4 through a flexible tube 48.

The top part of piston 52 cooperates with a duit 48, oil does not flow into cylinder 41, or the oil which had flown into said cylinder has suiflcient time to flow back through passage 50. Therefore piston 52 remains in its lower position so that it cooperates with projection 55 but not with projection 51. Th. refore the movement of lla toward the right produces the opening of cock 28 but the return-of Ila toward the left sliding part 53 guided by a support 54. Piston 52 is placed between two downward projections 55 and'51 of said part 53. Part 53 operates cock 28, through a lever 55.-

When'piston 52 is in its upper position it imparts its horizontal displacements to part 53 in both directions since it is engaged between the projections 55 and 51 of said part 53.

The downward displacement of piston 52 is limited by a partition 49 provided in cylinder. 41 so that the top part of the piston can never come below the bottom part of projection 55. When piston 52 is resting on partition 49, it can transmit its horizontal displacements toward the right to piece 53 through projection 55, but its does not close this cock.

Fig.2 shows a particular construction of the valve means including ball and spring 25. This construction provides two couplings 33 and 34 adapted to cooperate, respectively, with lines 22 and I5 (or 23 and I5) and passages 35 and 35 leading from said couplings respectively to chamber 2|. A removable piece carries the seat 35a of ball 25.

The storage tank of Fig. 3 is characterized by the fact that piston 5 is provided with packing elements having elastic sealing lips 31.- The line 3 through which oil under pressure is fed to I chamber 5 is fitted with a'check valve 39.

displacements toward the left no longer influence part- 53 because said piston now passes under projection 51 without touchingit. Partition 49 is provided with a check valve 5l' which permits fluid to flow freely from line 48 to the under face of piston 52, and said partition 49 is also provided with a passage 50 of very small section so that, in case of the pressure I in l4 and 48 dropping down to zero, the pressure existingcin the space between partition 49 and the under face, of piston 52 takes a certain time to drop back to zero. J

This connecting device works in the following manner: 1

It .will be supposed that when Ila is inclined toward the right, as shown by the drawing, line] I4 is connected with line 3. On the contrary. when Ila is turned toward the left, moving the whole of part 45, cylinder 41, and piston 52 toward the left, line i4 is not connected with 8.

In this. last mentioned position, there is no pressure in l4 nor in 48, so that piston 52 rests on partition 49.

Starting from the position shown, when Ila is pivoted toward the right, the whole of 45, 41

and piston 52 is also caused to slide toward theright. In the course of this movement, the top part of piston 52 bears against projection 55 v and imparts this movement toward the right to sliding member 53, which produces the opening of cock 28. a

The pressure fed to l4 by line'3 is transmitted through conduit 48 to the space under piston 52 and it causes said piston to move upwardly and to engage between projections 55 and '51.

Therefore, if everything is normal, when subsequently member Ila is pivoted toward the left, v this movement is transmitted to part 53 and cock 23 (which is thus closed) through piston 52 acting on projection 51. It will be noted that, during the short time necessary for this displacement, piston 52 remains in the upper position it occupied because oil has not had time to escape through the small passage 50 to any substantial amount.

0n the other hand, if the conditions are not 'normal, that is to say if at any time after the pivoting of control member He toward the right,

differentially operative by the respective fluid' there is a lack of pressure in line l4 and con- 75.

The present application is-a continuation in part of my prior patent application Ser. No.

'138,102,'fl1ed April 21, i937, and now' forfeited and abandoned.

While I have, in. the above description, dis-- closed what I deem to be practical and eflicient embodiments of the. present invention, it should be well understood that I do not wish to be limited thereto as changes can be devised in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

l. A system of the type described which comprises, in combination, a fluid pressure. responsive double acting device, a source of fluid pressure for supplying operating fluid to said device, a

main supply line leading to one side of said device for operation thereof in one direction,another main supply line leading to the other side of said device for operation thereof in the'other direction, a discharge line, distributor means for alternately connecting one of said main lines with said source and the otherwith said discharge line, an auxiliary line. leading to the same side of said device as said first mentioned main line, a source of fluid under pressure, means operative by said distributor means for connecting said auxiliary line with said second mentioned source of pressure when said distributor means is brought into the position'placing said first mentioned supply line in communication with its source of fluid pressure, and valve meansinterposed between said first-mentioned main supply line and said auxiliary line so as alternately to connect one with said device while disconnecting the other therefrom, these valve means being pressures in these two last mentioned lines respectively for connecting said auxiliary line with said device as soon as a breakdown causes a said second mentioned source of pressure with said auxiliary line, means operative by said distributor means for opening said cock when said distributor'means are in the position connecting said first mentioned line with said first mentioned source and normally closing said cock when said distributor means are in the other position, said cock operating means being further responsive to pressure variations in said first mentioned line so as to leave said cock in the opened position thereof when said distrib-. utor means is brought back into the second men- .tioned position thereof after a given drop of pressure has occurred in said first mentioned line in communication with said first mentioned source of pressure, and valve means interposed between said first mentionedmain supply line and said auxiliary line so as alternately to conmet one with said device and to disconnect the other therefrom, these valve means being differentially operative by the respective fluid pres suresin these two .last mentioned lines respectively for connecting said auxiliary line with said device as soon as a breakdown causes a given lack of pressure in the first mentioned main supply line in communication with said first mentioned source of pressure. V

3. A system of the type described which comprises-in combination, a fluid pressure responsive double acting device, a source of liquid under pressure for supplying operating fluid to said device, a main supply line leading to one side of said device for operation thereof in one direction,'another main supply line leading to the other side of said device for operation thereof mthe other direction, a discharge line, a distributor means for alternately connecting one of said main lines with said source and the other with said discharge line, an auxiliary line filled with liquid leading to the same side of said device as said first mentioned main line, a hydropneumatic accumulator, means, including a cock,

, ing said cock when said distributor means is in at least one fluid actuated device, a storage device containing a fluid under pressure; a movable fluid tight partition inside said device separating it into two chambers one of which contains a liquid and the other a gas, a main circuit connecting one of said chambers with said fluid actuated device, valve means inserted in said main circuit, at least one auxiliary independent circuit acting as a duplicate of the first one, connected with said other chamber includin means for supplying liquid to said auxiliary circuit and abutting into said valve means where the other position, said cock operating means" being further responsive to pressure variations in said first mentioned main line so as to leave said cock open when said distributor means. are brought back into the second mentioned position thereof after a drop of pressure having occurred in the first mentioned main line in communication with said source of fluid under pressure, and valve means interposed between said first mentioned main supply line and said auxiliary line it is connected with said main circuit, said valve means having anoutlet directly connected with said fluid actuated device and comprising a valve member subjected to the opposing action of the pressures prevailing in said two circuits and adapted to close the circuit having the lowest pressure, elastic reaction means adapted to act upon said valve member so as to close the auxiliary circuit when the plant,operates in normal condition.

5. A system of the type described which comprises, in combination, a fluid pressure responsive double acting device, a storage device containing a fluid under pressure, ,for supplying operating fluid, a movable fluid tight partition inside said device separating it into two chambers one of which contains a liquid and the other a gas, a main supply line connecting one of said chambers to one side of said double acting device for operation thereof in one direction, another main supply line connecting the same chamber to the other side of said double acting device for operation thereof in the other direction, a discharge line, distributor means for alternately connecting one of said main lines with said storage device and the other with said discharge line, an auxiliary line connecting the other of said chambers to the same side of said device as said first mentioned main line and including means for supplying liquid to said auxiliary line, and valve means interposed between said first mentioned supply line and said auxiliary line so as alternately to connect one with said double acting device while disconnecting the other therefrom, said valve means being differentially operative by the respective fluid pressures in these two last mentioned lines respectively for connecting said auxiliary line with said device as soon as the pressure in the first mentioned main line in communication with said first mentioned source of pressure drops by a given value below the pressure in said auxiliary line.

JEAN MERCIER. 

